Computational characterization of drug adsorption on silver nanoparticles

Drug overdose has become a serious social problem in the United States. Among the recreational drugs, the synthetic opioid compound fentanyl has become the latest leading source of death. Recently, the Fabris group has developed a rapid and accurate method for the detection of trace amount of fentanyl using silver nanoparticles and the surface enhanced Raman spectroscopy (SERS) technique. We have performed molecular dynamics (MD) simulations to elucidate the mechanism of drug adsorption on the nanoparticles. Specifically, we have examined the interactions of the recreational drugs fentanyl, norfentanyl, THC and heroin on a silver surface, and revealed that their adsorption arises from a combination of charge transfer, aromatic-metal and dispersion interactions. Our simulations have demonstrated why fentanyl adsorbs stronger than the other recreational drugs and provided crucial insight into the different signal enhancement in the SERS spectra.